This view characterises thinking as that factor in man through which he inserts himself spiritually into reality. (And, strictly, no one should confuse this kind of world-view, which is based on thinking as directly experienced, with mere Rationalism.) But, on the other hand, the whole tenor of the preceding argumentation shows that perception yields a determination of reality for human knowledge only when it is taken hold of in thinking. Outside of thinking there is nothing to characterise reality for what it is. Hence we have no right to imagine that sense-perception is the only witness to reality. Whatever comes to us by way of perception on our journey through life, we cannot but expect. The only point open to question would be whether, from the exclusive point of view of thinking as we intuitively experience it, we have a right to expect that over and above sensuous perception there is also spiritual perception. This expectation is justified. For, though intuitive thinking is, on the one hand, an active process taking place in the human mind, it is, on the other hand, also a spiritual perception mediated by no sense-organ. It is a perception in which the percipient is himself active, and a self-activity which is at the same time perceived. In intuitive thinking man enters a spiritual world also as a percipient. Whatever within this world presents itself to him as percept in the same way in which the spiritual world of his own thinking so presents itself, that is recognised by him as constituting a world of spiritual perception. This world of spiritual perception we may suppose to be standing in the same relation to thinking as does, on the sensuous side, the world of sense-perception. Man does not experience the world of spiritual perception as an alien something, because he is already familiar in his intuitive thinking with an experience of purely spiritual character. With such a world of spiritual perception a number of the writings are concerned which I have published since this present book appeared. The Philosophy of Spiritual Activity lays the philosophical foundation for these later writings. For it attempts to show that in the very experience of thinking, rightly understood, we experience Spirit. This is the reason why it appears to the author that no one will stop short of entering the world of spiritual perception who has been able to adopt, in all seriousness, the point of view of the Philosophy of Spiritual Activity. True, logical deduction--by syllogisms--will not extract out of the contents of this book the contents of the author's later books. But a living understanding of what is meant in this book by "intuitive thinking" will naturally prepare the way for living entry into the world of spiritual perception. TRUTH AND SCIENCE [15] I PRELIMINARY OBSERVATIONS